Beat the heat!

After a long, wet winter for many, the arrival of spring brings hope for drier, warmer weather, but it also signals the onset of heat stress risks for dairy herds. Technical Manager Philip Ambler shares his advice on how to support your herd this summer.

Robotic Milking
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As temperatures rise with the changing seasons, so does the likelihood of heat stress, posing significant challenges for dairy producers. High yielding cows in robotic systems can be particularly sensitive to rising temperatures, says Philip Ambler.

“Understanding the implications of heat stress and implementing effective mitigation strategies are crucial for maintaining herd health and productivity during the warmer months.” The ideal ambient temperature for dairy cows ranges between 5°C and 25°C.

“Even a slight increase in temperature, especially when coupled with high humidity, can trigger heat stress,” he says. “This condition not only compromises cow welfare, but can also lead to reduced milk production and fertility issues.”

When temperatures are higher cows may exhibit self-regulating behaviours, such as panting or drooling in an attempt to cool themselves. “Cows that are affected by heat stress can become lethargic, spending more time than usual lying down and therefore not visiting the feed barrier or robot as frequently as usual,” explains Philip.

Efforts to cool themselves down use up energy and redirects it away from other processes, including milk production. Rumen function can be reduced by heat stress too, with the pH of the rumen lowered due to loss of sodium bicarbonate from increased drooling. Fertility can also be affected, with studies suggesting that heat stressed cows are 63% less likely to conceive. In addition, cows in the early stages of pregnancy are more likely to suffer from early embryonic loss.

Feeding management

Philip advises farms to adjust feeding schedules to cooler times of the day, typically between 8 pm and 8 am, to encourage higher feed intakes. “This may be easier to do with automated feeding systems which can easily be adjusted to deliver more feed during the cooler parts of the day. Your account manager or nutritionist can advise on whether it is necessary to increase the energy density of diets by incorporating concentrates or by-products to compensate for reduced feed intake during hot weather. Where possible opt for higher quality and easily digestible forages to minimise heat generated from fermentation.”

Water supply

Always ensure ample access to clean and fresh water, as cows may drink up to an extra 100 litres per day during heat stress periods, he advises. Avoid crowding at water troughs by providing sufficient trough space to meet peak demand.

Housing and ventilation

Maintain well-ventilated housing to promote airflow and dissipate heat. “Research in the US has suggested that low airflow can reduce respiration rates in heat stressed animals by as much as 50%. Enhance natural ventilation by modifying building structures if necessary, such as adjusting sideboard spacing. Consider investing in new or improved fans if natural airflow is insufficient to keep temperatures at a comfortable level.”

Grazing Management

Cows in robotic systems with access to grazing are likely to choose to stay inside when the temperatures are high outside, he continues. “However it’s still good practice to ensure that cows have access to shade and ample shaded water troughs when outside.

“If necessary, adjust paddock rotations to ensure access to shade throughout the day. During extreme heat, consider keeping cows inside during the hottest times of day (over midday) to prevent heat stress.”

Pay attention to robot data

Data from the robot will flag up early signs of heat stress such as altered behaviour, reduced activity levels or fewer robot visits. It may also be particularly useful for heat detection in the warmer months as reduced activity levels can make it more difficult.

“If you’re not already signed up to OptiRobot, ask your account manager about how to make use of our data platform. It can increase the value of your data and means that we can assist you in spotting issues or trends.”


In a robotic system there is minimal handling anyway, but during hotter weather always carry out any handling tasks during the coolest parts of the day and avoid crowding animals into pens for extended periods, advises Philip. Limit time spent in pens to under an hour where possible to reduce heat stress.

Supplement support with Lintec

Omega-3 fatty acids have an important role to play in supporting cow fertility, health and performance. Supplementing cows with Lintec, a feed supplement made from a special strain of Linseed, ensures they are consuming optimal levels of omega-3 fatty acids.

“As well as supporting fertility by boosting progesterone levels and suppressing prostaglandin levels, Lintec also improves milk quality,” explains Philip. “As well as these direct performance benefits, Lintec has also been shown to help reduce methane emissions in dairy cows.”

As temperatures rise, proactive planning and implementation of heat stress mitigation strategies are essential for safeguarding the welfare and productivity of dairy herds, concludes Philip.

“By prioritising feeding management, water supply, housing, grazing practices, and handling procedures, dairy farmers can minimise the adverse effects of heat stress and ensure optimal herd performance even during the hottest months of the year.”

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